The present invention relates to a linear guide apparatus and, in particular, to a self-lubrication linear guide apparatus that allows a lubricant to be automatically supplied to a plurality of rolling elements, which are component parts of the linear guide apparatus and which are rolling within a slider, over a long period of time.
An exemplary conventional linear guide apparatus for ordinary use includes, as shown in FIG. 4, an axially extending guide rail 1 that has rolling grooves 3 on outer surfaces thereof, and a slider 2 that is engaged with the guide rail 1 so as to mount over the guide rail 1. The slider 2 includes a slider main body 2A and end caps 2B attached to both end portions of the slider main body. The slider main body 2A has not only rolling grooves formed on the inner surfaces of both sleeve portions 4 thereof so as to confront the rolling grooves 3 of the guide rail 1, but also rolling element return grooves that pass through the thick-walled portions of the sleeve portions. Each end cap 2B has curved grooves that allow the rolling grooves of the slider main body 2A to communicate with the rolling element return grooves that extend in parallel with the rolling grooves of the slider main body 2A. Thus, the rolling grooves, the rolling element return grooves, and the curved grooves on both ends provide rolling element circulation circuits. A large number of balls, which are the rolling elements, are loaded into the rolling element circulation circuits. The rolling elements within the rolling grooves of the slider 2 are retained by a retainer so that the rolling elements avoid falling away from the slider 2 when the slider 2 is removed from the guide rail 1.
The slider 2 that is engaged with the guider rail 1 moves smoothly along the guide rail through the rolling of the rolling elements accommodated within both rolling grooves that confront each other, and during such movement the rolling elements are endlessly circulating throughout the rolling element circulation passages within the slider.
Grease or lubricating oil is charged into the slider 2 from a grease nipple 7, so that the rolling elements are lubricated.
However, in the conventional linear guide apparatus having such a lubrication system that lubricating oil or grease is used as a lubricant as it is, i.e., without giving any special arrangement, the lubricant is consumed quickly especially when the apparatus is operated at high temperatures because the lubricant charged into the slider does not stay but flows outside the apparatus. Therefore, the conventional linear guide apparatus has encountered the problem that the lubricant must be replenished repeatedly at short intervals.